Chakravarti A, Phillips J A, Mellits K H, Buetow K H, Seeburg P H
Proc Natl Acad Sci U S A. 1984 Oct;81(19):6085-9. doi: 10.1073/pnas.81.19.6085.
Six restriction fragment length polymorphisms (RFLPs) detected in the human growth hormone-human chorionic somatomammotropin (hGH-hCS) gene cluster were studied in Mediterraneans, Northern Europeans, and American Blacks; the polymorphisms showed that, on the average, one of 500 bases in this cluster is variant. Haplotypes constructed for four of these RFLPs display strong nonrandom associations. However, the strongest associations were between RFLPs that are in homologous DNAs rather than between the physically closest RFLPs. From this and other evidence we argue that duplication of an ancestral hCS gene occurred at least twice, the second event being relatively recent. In other words, duplication of the hCS-L gene to produce the hCS-A gene occurred twice, so that hCS-A genes in humans may have independent origins. Our results imply that chromosomes with absent hCS genes (leading to hCS deficiency) may represent the nonduplicated ancestral unit rather than gene deletions.
对地中海人、北欧人和美国黑人的人类生长激素 - 人绒毛膜生长催乳素（hGH - hCS）基因簇中检测到的六种限制性片段长度多态性（RFLP）进行了研究；这些多态性表明，该基因簇中平均每500个碱基就有一个变体。针对其中四种RFLP构建的单倍型显示出强烈的非随机关联。然而，最强的关联存在于同源DNA中的RFLP之间，而非物理距离最近的RFLP之间。基于此及其他证据，我们认为一个祖先hCS基因的复制至少发生了两次，第二次事件相对较近。换句话说，hCS - L基因复制产生hCS - A基因的过程发生了两次，因此人类中的hCS - A基因可能有独立的起源。我们的结果表明，缺乏hCS基因（导致hCS缺乏）的染色体可能代表未复制的祖先单位，而非基因缺失。
